AzureBlobStorage AuthorizationPermissionMismatch error using User Managed Identities, Python SDK from AKS

Question

I'm running a Python app in AKS (as a Job, but doesn't matter), using the Azure Python SDK to access blob storage. I'm using a User Managed Identity for auth, using ManagedIdentityCredential with the client_id kwarg (see https://docs.microsoft.com/en-us/python/api/azure-identity/azure.identity.managedidentitycredential?view=azure-python). It is successfully able to query the IMDS endpoint and obtain a token, but I'm still hitting an error. Anybody has any idea about what setup I might be missing?

There are precious little docs about user managed identities overall, esp in relation to AKS and the blob store, and this error.

Successful IMDS token fetch:

2021-01-26 05:26:05,944 - azure.core.pipeline.policies.http_logging_policy - INFO - Request URL: 'http://REDACTED/metadata/identity/oauth2/token?api-version=REDACTED&resource=REDACTED&client_id=REDACTED'
2021-01-26 05:26:05,945 - azure.core.pipeline.policies.http_logging_policy - INFO - Request method: 'GET'
2021-01-26 05:26:05,945 - azure.core.pipeline.policies.http_logging_policy - INFO - Request headers:
2021-01-26 05:26:05,945 - azure.core.pipeline.policies.http_logging_policy - INFO -     'Metadata': 'REDACTED'
2021-01-26 05:26:05,945 - azure.core.pipeline.policies.http_logging_policy - INFO -     'User-Agent': 'azsdk-python-identity/1.5.0 Python/3.7.7 (Linux-4.15.0-1103-azure-x86_64-with-debian-9.12)'
2021-01-26 05:26:05,945 - azure.core.pipeline.policies.http_logging_policy - INFO - No body was attached to the request
2021-01-26 05:26:05,956 - azure.core.pipeline.policies.http_logging_policy - INFO - Response status: 200
2021-01-26 05:26:05,956 - azure.core.pipeline.policies.http_logging_policy - INFO - Response headers:
2021-01-26 05:26:05,956 - azure.core.pipeline.policies.http_logging_policy - INFO -     'Content-Type': 'application/json; charset=utf-8'
2021-01-26 05:26:05,956 - azure.core.pipeline.policies.http_logging_policy - INFO -     'Server': 'IMDS/150.870.65.486'
2021-01-26 05:26:05,956 - azure.core.pipeline.policies.http_logging_policy - INFO -     'Date': 'Tue, 26 Jan 2021 05:26:05 GMT'
2021-01-26 05:26:05,956 - azure.core.pipeline.policies.http_logging_policy - INFO -     'Content-Length': '1760'
2021-01-26 05:26:05,957 - azure.identity._internal.decorators - INFO - ManagedIdentityCredential.get_token succeeded
2021-01-26 05:26:05,957 - azure.identity._credentials.chained - INFO - ChainedTokenCredential acquired a token from ManagedIdentityCredential

Subsequent API call to blob.core.windows.net/.... errors:

  File "/usr/local/lib/python3.7/site-packages/azure/storage/blob/_blob_client.py", line 685, in upload_blob
    return upload_block_blob(**options)
  File "/usr/local/lib/python3.7/site-packages/azure/storage/blob/_upload_helpers.py", line 157, in upload_block_blob
    process_storage_error(error)
  File "/usr/local/lib/python3.7/site-packages/azure/storage/blob/_shared/response_handlers.py", line 150, in process_storage_error
    error.raise_with_traceback()
  File "/usr/local/lib/python3.7/site-packages/azure/core/exceptions.py", line 218, in raise_with_traceback
    raise super(AzureError, self).with_traceback(self.exc_traceback)
  File "/usr/local/lib/python3.7/site-packages/azure/storage/blob/_upload_helpers.py", line 105, in upload_block_blob
    **kwargs)
  File "/usr/local/lib/python3.7/site-packages/azure/storage/blob/_generated/operations/_block_blob_operations.py", line 233, in upload
    raise HttpResponseError(response=response, model=error)
azure.core.exceptions.HttpResponseError: This request is not authorized to perform this operation using this permission.
RequestId:defcc13f-101e-006c-6aa3-f321cb000000
Time:2021-01-26T05:26:06.0112926Z
ErrorCode:AuthorizationPermissionMismatch
Error:None

The blob storage resource in question has a role assignment to the user-managed identity, as a "contributor" to "This resource".

Code:

    managed_identity = ManagedIdentityCredential(client_id=mi_client_id)
    azure_cli = AzureCliCredential()
    credential_chain = ChainedTokenCredential(managed_identity, azure_cli)
    return BlobServiceClient(url_prefix, credential=credential_chain)

Versions: azure-identity 1.5, Python 3.7.7

I'm not sure our AKS Cluster has granted the user managed identity a role, and I'm not sure if that matters, or what else needs to be set up.

thanks

Evan Chan Evan Chan · Accepted Answer · 2021-02-02T01:24:27

It turns out the answer is that “Storage Blob Data Contributor” and “Storage Queue Data Contributor” roles BOTH have to be assigned to resolve the issue.

AzureBlobStorage AuthorizationPermissionMismatch error using User Managed Identities, Python SDK from AKS

2 Answers